1. Field of the Invention
The present invention relates to a method for performing gear shifting operation and indication for a vehicle having a manual transmission, more particularly to a method for indicating a driver gear shifting operation capable of running at a preferable shift position for optimum fuel consumption rate and an apparatus for realizing the method.
2. Description of the Prior Art
Recently, the situation and circumstance surrounding supply of oils has deteriorated and various research and development activities have been made in an attempt to improve efficient utilization of energy in each technical field in each industry. The situation is the same in the automobile industry, where various researches and developments for improving engines with better thermal efficiencies and for pursuing better methods for performing effective combustion of fuel for vehicles with less fuel consumption rate are sought. However, there is a problem that unless operations including acceleration operation and gear shifting operation are considered, it is not possible for a driver to sufficiently demonstrate the improved fuel consumption performance thus reached.
As a solution for this problem, a method for indicating to a driver preferable shift positions in optimum fuel consumption rates in g/ps. h corresponding to all running conditions are stored in a memory in advance as a data map and various calculations are performed in accordance with the data map and information signals detected by different detectors.
Although the above method results in preferable gear shifting indication to the driver relating to optimum fuel consumption, the problem is that a large number of memory elements or a large memory capacity is required in order to store voluminous data.
It turns out through many experiments done by the applicant that; supposing that the fuel consumption rate determined by the number of engine rotations N in rev./min and the engine load Q/N in 1/rev. is at the point G in the graph shown in FIG. 1 and one step shift-up operation is performed from the current shift position, the number of engine rotations N (i.e, engine speed) necessary for maintaining the same car speed in km/h in this condition is necessarily determined by the gear ratio of a transmission. Also, the horse power PS in ps necessary for maintaining the car speed is considered almost unchanged even if shifting is performed so that an expected engine load Q/N when shifting up one step can be calculated therefrom, and the fuel consumption rate after one step shift-up moves to G' in the graph or data map in FIG. 1. However, the angle of inclination .alpha. formed by the line connecting the two points G and G' and the horizontal line remains almost unchanged, regardless of shifting up and down for all running conditions, and it was confirmed by the applicant of this application that the angle is determined only by the conditions of the manual transmission.
Moreover, the equal fuel consumption rate curves F shown in FIG. 2 are prepared by plotting equal values among the fuel consumption rates determined by the number of engine rotations (i.e., engine speed) and the engine load Q/N. In FIG. 2, supposing that the current fuel consumption rate is located at the point J, the new position in the fuel consumption rate data map after shifting up moves to the point J' and it is preferable to perform a shift-up operation in view of the fuel consumption rate.
Alternatively, if the current fuel consumption rate is located at the point K, the fuel consumption rate K when performing shift-down operation moves to the point K' and it is apparent that the shift-down operation is favorable in view of the fuel consumption rate.